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42de23f7fd
AnalyzeBranch on X86 (and, previously, SPARC, which implementation was
copied from X86) tries to modify the branches based on block
layout (e.g. checking isLayoutSuccessor), when AllowModify is true.
The rest of the architectures leave that up to the caller, which can
call InsertBranch, RemoveBranch, and ReverseBranchCondition as
appropriate. That appears to be the preferred way to do it nowadays.
This commit makes SPARC like the rest: replaces AnalyzeBranch with an
implementation cribbed from AArch64, and adds a ReverseBranchCondition
implementation.
Additionally, a test-case has been added (also cribbed from AArch64)
demonstrating that redundant branch sequences no longer get emitted.
E.g., it used to emit code like this:
bne .LBB1_2
nop
ba .LBB1_1
nop
.LBB1_2:
And now emits:
cmp %i0, 42
be .LBB1_1
nop
llvm-svn: 257572
59 lines
1.3 KiB
LLVM
59 lines
1.3 KiB
LLVM
; RUN: llc -mtriple=sparc-none-linux-gnu < %s | FileCheck %s
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; This test checks that LLVM can do basic stripping and reapplying of branches
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; to basic blocks.
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declare void @test_true()
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declare void @test_false()
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; !0 corresponds to a branch being taken, !1 to not being takne.
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!0 = !{!"branch_weights", i32 64, i32 4}
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!1 = !{!"branch_weights", i32 4, i32 64}
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define void @test_Bcc_fallthrough_taken(i32 %in) nounwind {
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; CHECK-LABEL: test_Bcc_fallthrough_taken:
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%tst = icmp eq i32 %in, 42
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br i1 %tst, label %true, label %false, !prof !0
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; CHECK: cmp {{%[goli][0-9]+}}, 42
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; CHECK: bne [[FALSE:.LBB[0-9]+_[0-9]+]]
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; CHECK-NEXT: nop
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; CHECK-NEXT: ! BB#
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; CHECK-NEXT: call test_true
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; CHECK: [[FALSE]]:
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; CHECK: call test_false
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true:
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call void @test_true()
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ret void
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false:
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call void @test_false()
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ret void
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}
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define void @test_Bcc_fallthrough_nottaken(i32 %in) nounwind {
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; CHECK-LABEL: test_Bcc_fallthrough_nottaken:
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%tst = icmp eq i32 %in, 42
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br i1 %tst, label %true, label %false, !prof !1
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; CHECK: cmp {{%[goli][0-9]+}}, 42
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; CHECK: be [[TRUE:.LBB[0-9]+_[0-9]+]]
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; CHECK-NEXT: nop
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; CHECK-NEXT: ! BB#
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; CHECK-NEXT: call test_false
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; CHECK: [[TRUE]]:
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; CHECK: call test_true
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true:
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call void @test_true()
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ret void
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false:
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call void @test_false()
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ret void
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}
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